Method and apparatus for case hardening glass sheets



June 2, 1936. G. R FORD, JR 2,042,521

METHODAND APPARATUS FOR CASE HARDENING GLASS SHEETS Filed April 6, 1935 2 Sheets-Sheet 1 June 2, 1936. G, R. FQRD, JR I 2,042,521

METHOD AND APPARATUS FOR CASE HARDENING GLASS SHEETS Filed April 6, 1935 2 Sheets-Sheet 2 6504965 E Foo c/A.

Citorneg Patented June 2, 1936 4mural) STATES PATENT OFFICE ME'rnon ANDAPPABATUS Foa CASE :imminente GLASS smazli'rsf Application April s, 1935', serial No. 14,914

, 20 Claims.

The present invention relates to the case hardening of glass and more particularly to an improved method and apparatusforhardening or tempering glassI sheets o'r plates in a semi-continuous manner.

Generally speaking, such hardening consists in first heating a. sheet ot glass to approximately its point of softening and in then rapidly` chilling the same to place the outer surfaces :of the sheet under compression and the interior thereof under tension. manner have utility as a form of safety glass since -the treatment thereof not only materially increases the mechanical strength of the glass but also changes the breaking characteristics of the sheet, in that when broken it will disintegrate into innumerable small and relatively harmless fragments instead of breaking into large, dangerous pieces or splinters as in the case of ordinary glass sheets.

ln accordance with the present invention, there is provided an apparatus for case hardening glass sheets including a. furnace having a plurality of individual heating compartments which are adapted to be successively charged with glass sheets to be treated. A cooling means is associated with the furnace in such a manner that intermittent relative movement therebetween will effect successive alignment of the heating coinpartments with the cooling means as' the vvglass sheet within each succeeding compartment reaches the desired temperature. The heated sheet is then transferred from the furnace t0 tion with the accompanying drawings.

In the drawings wherein like numerals are employed to designate like parts throughout the same, Fig. 1 is a plan view of 'an apparatus con- Glass sheets hardened in this' the following description when taken in connec.

structed in accordance with the present invern-5 tion, A Fig. 2 is a. longitudinal vertical section taken d substantially on line 2-2 in Fig. 1A, f l* Fig. 3 is a transverse vertical section -thrqugh 5 one of the individual heating compartments ta.k znsubstantially on line 3 3 in Fig. Fig. 4 is a side elevation of a somewhat modi -1 fied form of apparatus. s Referring now to-Figs. l to 3 of the drawings. l0 the numeral III designates a rotatable furnace-'cf f y substantially cylindrical formatiohgprovided, with "a plurality of radially extending, equally spaced heating compartments II to I6 inclusive for receiving glass sheets to be treated. Upon rotation of the furnace, the several heatingcompartments are adapted to be successively aligned.

at predetermined intervals, with a' stationary' y coolingA apparatus I1 mounted at the .side of said furnace closely adjacent thereto. r".lh'e furnace'- 20 is supported for rotary movement upon a. plural# ity of circumferentially arrangedrhorizontal supporting rollers I8 which are engaged lby a metallic base plate I9 fixed to the bottom surface 0f the furnace. The furnace is mounted upon a 25 vertical shaft or spindle 20 received within a central opening 2| and journaledin the hearings 22 and 23 carried by suitable brackets 24 25 respectively.A Intermittent rotation`v of the-'fura nace III is preferably effected by means of a. wormv 30 26 meshing with a worm wheel 2l which is keyed to the vertical shaft 20 between Lthe bearings 22' and 23.

As best' shown in Figs. 2 and 3. each of the individual heating compartments Il .to I6 has ar'- 35 ranged therein, adjacent the top thereof, a pair of oppositely disposed roller runways 2l and 2i for receiving and supporting an overhead car-'- riage 30. Each of these runways comprises a seriesu of horizontally aligned flanged rolls I I, 40 mounted at the ends of stub shafts 32 which are' Journal'ed in bearings 33 secured to the adjacentA side wall of the compartment.v The carriage Il is of substantially inverted T shape in cross section; being provided with a at rectangular base portion 34 supported upon the rolls Il and an upwardly extending central rib 3S.

Glass sheets v36 to be heated may be suspended within the heating compartment from the base portion 3l of the carriage 30 by means of tongs or thelike 31. 'I'he base portion 3| of the car. riage is adapted to be Supported upon and to ticle f freely over the rolls 3l of the opposing runways 28 and 29 which are sumciently spaced from one 55 another'to permit the tongs 31 to hang therebetween without interference. The central rib of the carriage is preferably formed with an opening 38 adjacent its forward end for receiving a hook or other implement with which to move the carriage and the glass sheet suspended therefrom into and out of the furnace. Although only a single large sheet 36 has been shown in the compartment I5 in Fig. 2,l it will be understood that a suitable rack, adapted to carry a numberY of smaller sheets, may be suspended from the carrlage 30 if desired.

In order to heat the glass sheets to approximately their point of softening while in the furnace, electrical heating means comprising series of resistance units 39 and' 40 respectively zare mounted alongthe opposite side walls of each of the compartments II to'l6. A pair of baiiie plates 4I and 42, practicallyenclosing the heating units 39 vand 40, are positioned below ltheI runways 28 and 29, being spaced from each other in a manner to form a relatively narrow chambenor passage 43 therebetween within which the sheet 36 is adapted to be positioned during heating. AWith this arrangement each of the compartments I I to I6 is in eiect an individual heating furnace, and by the use of suitable regulating means the temperature of any one of the compartments can be controlled independently of the others. Electrical heating means of the muilied typevhas been found most desirable for this purpose because of the great importance of obtaining a uniform and accurately controlled heating of the .glass sheets. AIt will be understood however that any suitable type of heat may be used and that all of the compartments may be heated by a common heating means if desired. 't To minimize the escape of heat during charging and discharging of the furnace, the opening to each of the heatingcompartments II to I5 is preferably covered by a face plate 44 secured to the sidewall of the furnace I0 and provided with an opening 45 of sufficient size to permit the free passage therethrough of the glass sheets together with their carrying and supporting means. The compartments are adapted to b e closed during heating by doors 46 and 41 hinged to the face plate 44 and provided with suitable latching or locking means 48.'

As broughtout above, a plurality of heating compartments are adapted toi be successively served b'y a single cooling means and as illustrated in Fig. l, the cooling means I1 wil'l serve all of the compartments 'I I to `|6 of the furnace I0. Obviously, in the event that a furnace having a larger number of compartments were used or if the' relative heating time of the hardening cycle were shortened, it might become necessary orv desirable to use more than one cooling unit.

l Although the invention .is in no way limited to any particular type of cooling means, the cooling apparatus I1 illustrated in the drawings comprises a pair.' of fixed vertical supporting frames 49 and 50 carrying the spaced blower heads 5I and 52 respectively. The opposing faces of the blower heads are provided with a plurality of uniformly spaced nipples 53 through which compressed air, supplied to the heads through flexible conduits 54 and 55, may be' discharged. Carried at the upper ends of the frames 49 and 50 are the horizontally arranged roller runways 55 and 51 respectively. These runways are similar in construction to the supporting runways 29 and 29 in each of the heating compartments I i to I5 and each includes a plurality of horizontally artaneously through the nipples 53.

ranged rolls 5l adapted to align with the rolls 3| of the runways 28 and 29 upon proper rotary movement of the furnace I 0 to move successive compartments into alignment with the cooling apparatus I1.

When the furnace I0 is moved into discharging position, the doors 45 and 41 of the heating compartment opposite the cooling apparatus I1 are opened to permit the operator to engage the opening 38 in the' central rib 35 of the carriage I9 with a suitable implement and to pull the carrlage from the runways 28 and 29 onto the runways 55 and 51. With the carriage 30 in the latter position, the glass sheet l36 will be sus` pended directly between the blower heads 5I and 52 and may be rapidly chilled by blasts or jets of air directed onto both sides of the sheet simul- The blower heads may be maintained stationary or caused to oscillate or otherwise move in the plane of. the sheet. In operation, intermittent rotary movement imparted to the. furnace ill at regular intervals to cause the heating compartments II to I6 to be successively and repeatedly aligned with the cooling means I1. As each compartment is brought into such position, the glass Isheet is removed therefrom as explained above after which.

the furnace is again rotated t0 move the compartment which has just been emptied into loadtiming of the furnace movements and the temv perature in the compartments is'so controlled.l that during the travel of any one compartment from the charging position A to the discharging position B, the glass sheet 3B contained therein will be heated to substantially its point of softening which, for ordinary at glass', is in the neighborhoOd of 1250 F. When the doors 46 and`41 are opened as shown in Fig. 1 to permit removal of the heated sheet from the compartment in discharging position, they will form a substantially continuous passage between the heating compartment and the cooling apparatus to protect and shield the heated sheet as it passes from the former to the latter.

A. plurality of glass sheets will therefore be undergoing treatment simultaneously, the sheets within the furnace being in progressively different stages oi' heating so that as each sheet reaches a predetermined temperature, it will be i inposition to be discharged from the furnace to 1' the cooling means. As the sheet is being removed from one compartment, an untreated sheetis being introduced into the compartment just previously emptied. This design'of apparatus and method of operation will result-fin a` the heated sheet from the furnace to the cooling means and the subsequentl removal of the sheet after chilling. Such a cycle can be canied out with the apparatus illustrated in Fig. 1` by imparting intermittent rotary movement to the furnace l0 at intervals of one minute each. Thus, an untreated sheet of glass is introduced into the furnace every minute and ve minutes will be required to advance the sheet from the loading position A to the discharge position B, during which time the said sheet will be brought to the desired temperature. Successive compartments are brought into alignment with the cooling means upon each movement of the furnace, at one minute intervals, and since the actual cooling time is 45 seconds, fteen seconds will be allowed for transferring the sheet from the furnace to the cooling means and its subsequent removal therefrom. Since a single cooling apparatus is adapted to serve a plurality of heating compartments, the cooling apparatus as well as the furnace will be in substantial continuous` operation, thereby reducing to a minimum loss of time of either the machine or the operator in charge thereof.

In Fig. 4 of they drawings there has been illustrated a modified form of apparatus which is similar in design and operation to that shown in Figs. 1 to 3 except that the heating furnace 59 is stationary while the cooling apparatus, desig. nated in its entirety by the numeral 60, is adapted to revolve about the furnace. To this end, the blower units 6i are mounted upon a truck 82 provided with wheels 63-which run on a circular track 64 extending entirely around the furnace.

A worm wheel 65 is rotatably mounted directly above the center of the furnace 59 and has driving connection with the cooling apparatus 60 by means of ahorizontal bar 66 and a vertical bracket 61. The cooling apparatusll is caused to align with successive heating compartments of the furnace byintermittent movement at regular intervals of the truck 62 along the track 64. This movement is imparted to the truck by means of a Worm 68 meshing with and driving the worm wheel y65.

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodimentof the same, andthat various changes in the shape, size and arrangement of parts maybe resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In apparatus for case hardening glass sheets, a furnace including a plurality of heating compartments for receiving the sheets to be treated, means for heating said compartments, cooling means associated with said furnace and adapted to receivev the heated glass sheets therefrom, and means for causing intermittent relative movement in one direction between the furnace and cooling means to effect successive and repeated alignment of each of the heating compatments with said cooling means.

2. In apparatus for case hardening glass sheets, a furnace including a plurality of radially extending heating compartments for receiving the sheets to be treated, means for heating said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, and means for causing rela-- tive movement between the furnace and cooling means to effect alignment of any one of said heating compartments withsaid cooling means.

3. In apparatus for case hardening glass sheets, a furnace including a plurality of heating compartments for receiving the sheets to be treated. means for heating said compartments, cooling means associated with said furnace and adapted. to receive the heated glass sheets therefrom, and means for causing relative rotary' movement be- 5 tween the furnace and cooling means to eiectsuccessive alignment of the heating compartments with said cooling means.

4. In apparatus for case hardening glass sheets, a furnace including a plurality of radially extending heating .compartments for receiving the sheets to be treated, means for heating said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, and means for causing relative movement between the furnace and cooling means about a common center to place the cooling means in operative relation with successive heating compartments.

5. In apparatus for case hardening glass sheets, a furnace including a plurality oil heating compartments for receiving the sheets; to be treated, means for heating said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, and means for effecting movement of the furnace relative to -said cooling means to bring any one of the heating compartments into operative relation with the cooling means. f

6. In apparatus for case hardening glass sheets, a furnaceu including a plurality of radially extending heating compartments for receiving the sheets to be treated, means for heating-said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, and means for rotating the furnace to bring any one of the heatingcompartments into operative relation with the cooling means. l 1

'7. In apparatus for case hardening glass 40 sheets, a furnace including a plurality, of heating compartments for receiving the sheets to be treated, means for heating said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets there- 45 from, and means for eifecting intermittent movement of the cooling means in one direction relative to the furnace to bring said cooling means into succcessive and repeated alignment with each one of the heating compartments.

8. In apparatus for case hardening glass sheets, a furnace including a plurality of radially extending heating compartments for receiving the sheets to be treated, means for heating said compartments, cooling means assciated with said 55 furnace and adapted to receive the heated glass sheets therefrom, and means for revolving the cooling means about the furnace to bring said cooling means into operative relation with any one of the heating compartments. 50

9. In apparatus for case hardening ,glass sheets, a furnace including a plurality of heating compartments for receiving the sheets to be sheets, a furnace including a plurality of heating 75 ly .extending heating compartments for receivingglass sheets to. be. treated, 'means'for 'heating vsaid compartments, -fcooling means .associated with said furnace. and adapted to receive'theheated glass sheets therefrom, means .for effecting in-` termittent movementr of the furnace in one direction relative to .said cooling'means to bring the heating compartments into successive and repeated alignment' with the coolingmeans. and sheet supporting means movable horizontally between the furnace and 'cooling means to position the glass sheets during treatment.

l2.` In. apparatus for case vhardening glass sheets, a furnace including .a plurality of heating compartments fonz-receiving the sheets, to be treated, heating means for said compartments,

` cooling means associated withv said furnace and adapted to receive. the heated glass sheets therefrom,V movable -carriages for supporting said sheets during treatment, al runway associated with each of the heating compartments for supporting one of said carriages, a .supporting runway associated withsaidcooling means and adaptedto receive the caniages from said first mentioned runways, and means for .providing relative movement between the. furnace and cooling means to effect; alignment of-:the supporting runway associated with any. one ,of -the -heating. compartments. with Ithef runway associated with .said cooling means. v

13. In. apparatus for case hardening glass sheets, a `furnaceincluding a plurality of radial-.- ly extending heating compartments for." receiving the sheets to be treated, heating means for said `compartments, cooling means associated with said .furnace and;v adapted-toreceive the heated glass sheets therefrom, movable 'care riages for supporting said '.sheets .during treatment,...a'. horizontal runway- .arrangedff within each of said heatingwompartments .fora-sup'- porting. ,.one of 4said carriages, a horizontal supporting runway associated with. said cooling meansv and adapted to receive the *carriages from said first. mentioned runways, land means Afor causing relative movement between the. furnace and cooling means toelect alignment of the runway within anyone ofcthe heating compartments with the'runway associated. with said coolingmeansu.

14. In apparatusQfor case hardening glass sheets,.a furnace including a plurality of heating compartments for receiving the sheets to be treated, heating rmeans for said compartments,

cooling. means associated with said furnace and adapted to receive the heated glass sheets therefrom, movable carriages for supporting said sheets during-treatment, a runway associated with each ofsaid heating compartments for supporting one of'said carriages, a supporting runway associated with said cooling means and adapted-'wreeeive .macarrlages from and am mentioned `runways.-

for causing movement of the furnace relative to said cooling means toeiIect alignment of the supporting runway assoclated with any one of the heating compartments with-the runway associated with said' cooling means.

- 15. 'In apparatus for case hardening glass sheets, a furnace including a plurality of radially extending heating compartments for receiving the sheets to be treated, heating means for said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, movable carriages for supporting said sheets during treatment, a horizontal runway arranged within each of said heating compartments for supporting one of said carriages, a horizontal supporting runway associated with said cooling means and adapted. vto receive the carriages from said first mentioned runways. and means for rotating the furnace relative to the cooling means to bring the supporting runway within any one of the heating compartments into alignment with the runway associated with the cooling means.

16. In apparatus for case hardening glass sheets, a furnace including a plurality of heating cornpartments for receiving the sheets to be treated, `heating means for said compartments, ycoolin means associated with said furnace and adapted to receive the heated glass sheets therefrom, movable carriages forsupporting said sheets during treatment, .a runway associated with each of said heating compartments for supporting one of said carriages,.`a supporting runway associated with said cooling means and adapted to receive the carriages from said first mentioned runways, and means for effectingv movement of said cooling means relative -to said furnace to bring the supporting runway associated with the' cooling means into alignment with the runway associated with any one ofthe heating compartments.

17. In apparatus for case hardening glass sheets. a furnace -inciuding a plurality of radially e'xtending heating compartments for receiving the sheets to Vbe treated, heating means for said compartments, cooling means associated with said furnace and adapted to receive the heated glass sheets therefrom, movable carriages for support'- ing said sheets during treatment, a horizontal runway arranged within each of said beating compartments for supporting one of said carriages, a horizontal supporting runway associated with said cooling means and adapted to receive 'the carriages from said nrst mentioned runways, and means for revolving said cooling meansabout said furnace to bring-the supporting runway. associated.. with said cooling means into alignment with the supporting runway within any one of the heating compartments.

.18. The method of case hardening glass sheets,

v which consists in successively charging a plurality of ,untreated sheets of glass into a furnace, heating each -sheet independently of the others to substantially the point of softening of the glass while in said furnace, maintaining the sheets in progressively different stages .of heating, successively removing the sheets from the furnace when they reach a predetermined temperature, A.

and in rapidly chilling each sheet as lt is removed from the furnace to case harden the same.

19. 'I he method offcase hardening glass sheets. which consists in successively charging a furnace with untreated sheets of glass, heating each sheet independently of the others to substantially .the

point of softening ofthe dass while in said lfurnace, maintaining the sheets in progressively ture when it reaches the point of discharge, successvely removing the heated sheets from the furnace at 'the point of discharge, and in subjecting each sheet as it is removed from the fur' nace to a sudden cooling action to case harden the same.

20. The method of case hardening glass sheets,

which consists in successively charging a plurality of untreated sheets of glass into a. furnace, heating each sheet independently of the others to substantially the point of softening of the glass while in said furnace whereby the sheets will be in successive stages of heating, providing a common cooling means movable into alignment with any one of the glass sheets when such sheet reaches the desired temperature, and in successively transferring the heated sheets from the furnace to the cooling means and rapidly chilling the same to eiect case hardening thereof.

' GEORGE R. FORD, JR. 

